#include <gst/gst.h> static GMainLoop *loop = NULL; static GstElement *backpipe = NULL; static gint stream_id = -1; #define PCMU_CAPS "application/x-rtp, media=audio, payload=0, clock-rate=8000, encoding-name=PCMU" static GstFlowReturn new_sample (GstElement * appsink, GstElement * rtspsrc) { GstSample *sample; GstFlowReturn ret = GST_FLOW_OK; g_assert (stream_id != -1); g_signal_emit_by_name (appsink, "pull-sample", &sample); if (!sample) goto out; g_signal_emit_by_name (rtspsrc, "push-backchannel-buffer", stream_id, sample, &ret); out: return ret; } static void setup_backchannel_shoveler (GstElement * rtspsrc, GstCaps * caps) { GstElement *appsink; backpipe = gst_parse_launch ("audiotestsrc is-live=true wave=red-noise ! " "mulawenc ! rtppcmupay ! appsink name=out", NULL); if (!backpipe) g_error ("Could not setup backchannel pipeline"); appsink = gst_bin_get_by_name (GST_BIN (backpipe), "out"); g_object_set (G_OBJECT (appsink), "caps", caps, "emit-signals", TRUE, NULL); g_signal_connect (appsink, "new-sample", G_CALLBACK (new_sample), rtspsrc); g_print ("Playing backchannel shoveler\n"); gst_element_set_state (backpipe, GST_STATE_PLAYING); } static gboolean remove_extra_fields (GQuark field_id, GValue * value G_GNUC_UNUSED, gpointer user_data G_GNUC_UNUSED) { return !g_str_has_prefix (g_quark_to_string (field_id), "a-"); } static gboolean find_backchannel (GstElement * rtspsrc, guint idx, GstCaps * caps, gpointer user_data G_GNUC_UNUSED) { GstStructure *s; gchar *caps_str = gst_caps_to_string (caps); g_print ("Selecting stream idx %u, caps %s\n", idx, caps_str); g_free (caps_str); s = gst_caps_get_structure (caps, 0); if (gst_structure_has_field (s, "a-sendonly")) { stream_id = idx; caps = gst_caps_new_empty (); s = gst_structure_copy (s); gst_structure_set_name (s, "application/x-rtp"); gst_structure_filter_and_map_in_place (s, remove_extra_fields, NULL); gst_caps_append_structure (caps, s); setup_backchannel_shoveler (rtspsrc, caps); } return TRUE; } int main (int argc, char *argv[]) { GstElement *pipeline, *rtspsrc; const gchar *location; gst_init (&argc, &argv); if (argc >= 2) location = argv[1]; else location = "rtsp://127.0.0.1:8554/test"; loop = g_main_loop_new (NULL, FALSE); pipeline = gst_parse_launch ("rtspsrc backchannel=onvif debug=true name=r " "r. ! queue ! decodebin ! queue ! xvimagesink async=false " "r. ! queue ! decodebin ! queue ! pulsesink async=false ", NULL); if (!pipeline) g_error ("Failed to parse pipeline"); rtspsrc = gst_bin_get_by_name (GST_BIN (pipeline), "r"); g_object_set (G_OBJECT (rtspsrc), "location", location, NULL); g_signal_connect (rtspsrc, "select-stream", G_CALLBACK (find_backchannel), NULL); gst_element_set_state (pipeline, GST_STATE_PLAYING); g_main_loop_run (loop); return 0; }